try libb2-1 instead of libb2-dev

[aryairani]

1. Switched libb2-dev for libb2-1 after Tweak crypto ffi for better dependencies #4900, to see if it would still build as well. Initially we couldn't tell because of a bug in the caching, which prevented a full build/test from being attempted.

2. However, by switching the cache keys in 473c7b4 / https://github.com/unisonweb/unison/actions/runs/8841328469, we do see a jit-binary-macOS-12 which includes libb2.1.dylib.

3. Next, however, I refactored the CI workflow to try to fix the original caching bug, and the resulting builds no longer redistribute libb2.

4. I wondered whether this was due to Tweak crypto ffi for better dependencies #4900 breaking something for macOS, but given (2), it doesn't seem possible. I wondered whether it was due to (1), but given (2), it doesn't seem to be that either. So I must have broken something in (3), but I don't know what yet.

5. Okay, it seems that the answer is that libb2 needs to be installed before raco exe; it's not enough for it to be installed before raco distribute.

6. And with (5), libb2-1 with Tweak crypto ffi for better dependencies #4900 (1) is fine.

[aryairani]

Some notes:

time brew install minimal-racket
real    0m15.298s
user    0m10.118s
sys     0m6.533s

bash-3.2$ time brew install libb2
real    0m3.627s
user    0m2.551s
sys     0m0.982s
bash-3.2$ 

[aryairani]

$ time /usr/local/Cellar/minimal-racket/8.11.1/bin/raco pkg install --auto compiler-lib
real    0m11.968s
user    0m17.625s
sys     0m3.330s

[aryairani]

$ time /usr/local/Cellar/minimal-racket/8.11.1/bin/raco pkg install --auto --skip-installed unison-jit-src/unison/
real    4m32.342s
user    8m10.447s
sys     0m43.179s